Rescuing EXIF GPS from iPhone 17 HEIC, in a browser-only app

My wife teaches outdoor-nature classes in Taipei and drops photos into TrailPaint , a small browser-only tool I built so she could make trail maps for her class handouts without wrestling with Canva. Drag GPX in, drop photos on the map, export a PNG. The whole thing runs in the tab. One of the features she relies on is auto-placement: drop twenty photos and each one lands on its own spot because the browser reads the EXIF GPS tag and drops a card there. It's the part of the product that feels mo